1. Field of the Invention
The present invention relates to a mold for injection molding resin or the like, an apparatus for disassembling and assembling the same and a method for said disassembling and assembling.
2. Related Background Art
The above-mentioned mold, which is often disassembled and assembled for the purpose of in-service inspection and repair, is constructed so that a movable mold plate is positioned opposite to a fixed mold plate, and a return pin extends through the movable mold plate to allow its end to face the fixed mold plate and is slidably fitted with the movable mold plate. A return spring is provided between an ejector plate supporting an ejector pin and the movable mold plate. Therefore, upon removing a movable side mounting plate from the movable mold plate in order to disassemble the mold, said return spring functions so as to expel the ejector plate supporting the ejector pin, thereby causing considerable danger and also eventually causing damage to the components.
For this reason it has been practiced, as shown in FIG. 7, that the ejector plate 105 (composed of two plates 105a, 105b in the illustrated case) is provided with a penetrating hole 112, 113 accessible through a penetrating hole 111 formed in a movable side mounting plate 107 and the movable mold plate 101 is provided with a threaded hole 114. A bolt 110 is screwed into said threaded hole 114 through the penetrating holes 111, 112, 113 prior to the disassembling of the mold, thereby allowing the movable mold plate 101 to support said ejector plate 105. Therefore, the ejector plate 105 is not expelled by elastic force of the return spring 106 when said movable side mounting plate 107 is detached. Subsequently an ejector pin 104 is removed, and the return spring 106 is loosened while the bolt 110 is unscrewed, thereby extracting the return pin 103 from the movable mold plate 101.
However, such construction increases the cost of the mold, because the threaded hole 114 and the through holes 111, 112, 113 have to be formed in the movable mold plate 101, ejector plate 105 and mounting plate 107, respectively, so as to pass the bolt 110 therethrough and secure it in order to support the ejector plate 105. Also, since the mounting position of said bolt 110 does not coincide with the line of elastic force of the return spring 106, the elastic force applied to the ejector plate 105 is unbalanced, and it is cumbersome and difficult to remove the return pin 103 while the bolt 110 is unscrewed.